Due to the rapid development of science and technology, various electric devices emerge in the market and are traded and used globally. However, the state grid parameters in different countries may be varied; for example, some high-power pure inductive or resistive load devices, such as 110 VAC hair dryer, hair straightener, coffee maker, etc., designed for a state where a 110 VAC grid is applied, cannot be used in another state where a 220 VAC grid is applied. As a result, the resource is wasted and the user experience is degraded.